Apparatus for reproducing data from information storage medium having multiple storage layers with optimal power control (OPC) areas and buffer areas

ABSTRACT

An information storage medium and an apparatus for recording and/or reproducing the information storage medium capable of controlling optimal recording power without an influence of an optimal power control (OPC) area in a layer upon an OPC area in a different layer. The information storage medium includes at least one information storage layer including an optimal power control area for obtaining an optical recording condition. OPC areas in adjacent information storage layers are disposed within different radiuses of the information storage medium. Accordingly, even when the information storage medium is made eccentric or has a manufacturing error, a recording property of the information storage medium is prevented from being degraded due to an influence of an OPC area in an information storage layer upon an OPC area in an adjacent information storage layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 10/866,087,filed on Jun. 14, 2004, now pending in the U.S. Patent and TrademarkOffice, which claims the benefit of Korean Patent Application No.2003-62855, filed on Sep. 8, 2003, in the Korean Intellectual PropertyOffice, and the benefits of U.S. Provisional Patent Application Nos.60/477,793 and 60/483,233, filed on Jun. 12, 2003 and Jun. 30, 2003,respectively, the disclosures of which are incorporated herein in theirentirety by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to recordable information storage media,and more particularly, to an information storage medium designed tocontrol optimum writing power in optimal power control (OPC) areas evenwhen eccentricity occurs among a plurality of information storage layersand a method and apparatus for recording/reproducing data on/from theinformation storage media.

2. Description of the Related Art

General information storage media are widely used as informationrecording media of optical pickup apparatuses for recording/reproducingdata in a non-contact way. Optical disks are used as the informationstorage medium and are classified as compact disks (CDs) or digitalversatile disks (DVDs) according to their information storage capacity.Examples of recordable, erasable, and reproducible optical disks are650MB CD-R, CD-RW, 4.7 GB DVD+RW, and the like. Furthermore, HD-DVDshaving a recording capacity of 25 GB or greater are under development.

As described above, information storage media have been developed tohave a greater recording capacity. The recording capacity of aninformation storage medium can be increased in two representative waysby: 1) reducing the wavelength of a recording beam emitted from a lightsource; and 2) increasing the numerical aperture of an objective lens.In addition, there is another method of forming a plurality ofinformation storage layers.

FIG. 1 schematically shows a dual-layered information storage mediumhaving first and second information storage layers L0 and L1. The firstand second information storage layers L0 and L1 include first and secondoptimal power control (OPC) areas 10L0 and 10L1, respectively, forobtaining an optimal writing power and first and second defectmanagement area (DMAs) 13L0 and 13L1, respectively. The first and secondOPC areas 10L0 and 10L1 are disposed to face each other.

Data is recorded in the first and second OPC areas 10L0 and 10L1 usingvarious levels of writing power to find the optimum writing power.Hence, data may be recorded at a power level higher than the optimumwriting power. Table 1 shows variations in the jitter characteristics ofeach of the first and second information storage layers L0 and L1 whendata is recorded in the OPC areas with different levels of writingpower.

TABLE 1 Writing power about 20% higher than Normal writing power normalwriting power L0 Writing Unwritten Writing Written Writing Written L1Unwritten Writing Written Writing Written Writing Jitter L0 5.9% 6.0%5.8% 5.9%->6.4% L1 6.3% 6.2% 6.3% 6.2% -> 6.3% Writing L0 6.4 6.3 6.37.5 6.4 Power L1 6.0 6.0 6.2 6.0 7.2

According to Table 1, if data is recorded with normal writing power, thejitter characteristics of the first or second information storage layerL0 or L1 remain constant. On the other hand, if data is recorded withwriting power about 20% higher than the normal writing power, the jittercharacteristics of the OPC area of a first or second information storagelayer L0 or L1 in which data has already been recorded are degraded. Ifdata is recorded on one of the first and second information storagelayers L0 and L1 with writing power more than 20% higher than the normalwriting power, it can be expected that the jitter characteristics of theother information storage layer may be further degraded.

Hence, if the first and second OPC areas 10L0 and 10L1 of the first andsecond information storage layers L0 and L1 exist within an equal radiusas shown in FIG. 1, one of them may not be usable.

The recording status of one of the first and second OPC areas 10L0 and10L1 may affect the recording characteristics of the other OPC area. Forexample, as shown in FIG. 2A, if data has been recorded on a part 10L0_Aof the first OPC area 10L0 and no data has been recorded on the residualarea 10L0_B thereof, the recording property of a part of the second OPCarea 10L1 which corresponds to the occupied part 10L0_A of the first OPCarea 10L0 is different from that of a part of the second OPC area 10L1which corresponds to the unoccupied part 10L0_B of the first OPC area10L0. In other words, since the transmittance of the laser with respectto the occupied part 10L0_A of the first OPC area 10L0 is different fromthe transmittance of a laser with respect to the unoccupied part 10L0_Bthereof, the recording property of the second OPC area 10L1 may beirregular over the area.

As described above, if the first and second OPC areas are disposedwithin an equal radius, they may not properly function.

During the manufacture of an information storage medium, eccentricitymay occur. For example, an information storage medium having a singleinformation storage layer may have eccentricity of about 70-80 μm(p-p)(where p denotes a peak). To manufacture an information storage mediumhaving first and second information storage layers L0 and L1, the firstand second storage layers L0 and L1 are separately manufactured and thenattached to each other. When eccentricity occurs during the manufactureof each of the first and second information storage layers L0 and L1,they may be attached to each other such that areas of the firstinformation storage layer L0 are not aligned with those of the secondinformation storage layer L1 as shown in FIG. 2B.

When the first and second OPC areas 10L0 and 10L1 are not in line,overlapped areas generated due to the out-of-line arrangement may affecteach other. For example, if data is recorded on the first OPC areaOPC_L0 using higher power than the normal writing power, the first OPCarea OPC_L0 adversely affects a defect management area (DMA_L1) of thesecond information storage layer L1 because the DMA_L1 contacts a part Cof the first OPC area 10L0. Also, a part D of the second OPC area OPC_L1may adversely affect a part of the first information storage layer thatcontacts the part D, and thus the part may not be used.

SUMMARY OF THE INVENTION

An aspect of the present invention provides an information storagemedium including an area in which optimum power control (OPC) isperformed, thereby preventing an area other than the OPC area from beingaffected by possible eccentricity.

Additional aspects and/or advantages of the invention will be set forthin part in the description which follows and, in part, will be obviousfrom the description, or may be learned by practice of the invention.

According to an aspect of the present invention, an information storagemedium includes at least one information storage layer including an OPCarea for obtaining an optical recording condition. OPC areas in adjacentinformation storage layers are disposed within different radiuses of theinformation storage medium.

According to an aspect of the present invention, when the OPC areas inthe adjacent information storage layers are apart from each other asmall distance in a radial direction of the information storage medium,the distance corresponds to at least a tolerance required uponmanufacture of the information storage medium.

According to an aspect of the present invention, buffer areas eachhaving a size corresponding to at least the tolerance is disposed onboth sides of each of the OPC areas.

According to an aspect of the present invention, a length of the bufferarea in the radial direction of the information storage medium is in therange of 5 to 100 μm.

According to an aspect of the present invention, an area for storingreproduction-only data is disposed in an information storage layer suchas to face an OPC area of an adjacent information storage layer.

According to another aspect of the present invention, an informationstorage medium includes a plurality of information storage layers eachincluding an OPC area for obtaining an optical recording condition. AnOPC area in an odd-numbered information storage layer and an OPC area inan adjacent even-numbered information storage layer are disposed withindifferent radiuses of the information storage medium such as not to faceeach other even when each of the information storage layers has amanufacturing error.

According to another aspect of the present invention, the informationstorage medium includes a defect management area and a user data area. Abuffer area is included between the defect management area and the userdata area.

According to another aspect of the present invention, an area forstoring reproduction-only data may be disposed in an information storagelayer such as to face an OPC area of an adjacent information storagelayer.

According to another aspect of the present invention, an informationstorage medium includes a plurality of information storage layers, eachincluding an OPC area for obtaining an optical recording condition andan area for storing reproduction-only data. An OPC area in aninformation storage layer is disposed to face a reproduction-only areaof an adjacent information storage layer.

According to another aspect of the present invention, thereproduction-only area may be larger than the OPC area.

According to another aspect of the present invention, the buffer areasmay be disposed at both sides of the OPC area, and each of the bufferareas may have a size obtained in consideration of at least one of thefollowing factors: an error in the determination of a start position ofeach area; a size of a beam for recording and reproduction; andeccentricity.

According to another aspect of the present invention, the buffer areasare disposed at both sides of the optimal power control area, and thebuffer area located in front of the optimal power control area may havea size corresponding to a pair of disk-related information and diskcontrol data recorded once.

According to another aspect, a method of minimizing interference betweena first optimal power control area in a first information storage layerand a second optimal power control area in a second information storagelayer of an information storage medium, by disposing the first optimalpower control area such that no overlap occurs with the second optimalpower control area is provided.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and/or other aspects and advantages of the present inventionwill become more apparent by describing in detail exemplary embodimentsthereof with reference to the attached drawings of which:

FIG. 1 illustrates a layout of a data area of a conventionaldual-layered information storage medium;

FIGS. 2A and 2B are views illustrating the influence of an OPC area uponan area other than the OPC area in the conventional dual-layeredinformation storage medium of FIG. 1;

FIG. 3A illustrates a layout of a data area of a dual-layeredinformation storage medium according to an embodiment of the presentinvention;

FIG. 3B illustrates a layout of a data area of a single-layeredinformation storage medium according to an embodiment of the presentinvention;

FIGS. 4A and 4B illustrate different eccentric states of thedual-layered information storage medium of FIG. 3A;

FIG. 5A illustrates a layout of a data area of a four-layeredinformation storage medium according to an embodiment of the presentinvention;

FIG. 5B illustrates an eccentric state of the four-layered informationstorage medium of FIG. 5A;

FIG. 6A illustrates a variation of the dual-layered information storagemedium of FIG. 3A;

FIGS. 6B and 6C illustrate different eccentric states of thedual-layered information storage medium of FIG. 6A;

FIG. 7A illustrates another variation of the dual-layered informationstorage medium of FIG. 3A;

FIG. 7B illustrates a variation of the single-layered informationstorage medium of FIG. 3B;

FIG. 8 illustrates a layout of a data area of a dual-layered informationstorage medium according to another embodiment of the present invention;

FIG. 9 illustrates a variation of the dual-layered information storagemedium of FIG. 8;

FIG. 10 is a block diagram of an apparatus for recording/reproducinginformation to/from an information storage medium according to anembodiment of the present invention; and

FIG. 11 is a block diagram of a disk drive in which the apparatus ofFIG. 10 is implemented.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the embodiments of the presentinvention, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to the like elementsthroughout. The embodiments are described below to explain the presentinvention by referring to the figures.

Referring to FIGS. 3A and 3B, an information storage medium according toan embodiment of the present invention includes at least one informationstorage layer, each of which includes an optimal power control (OPC)area for obtaining optimal power. The OPC areas are disposed withindifferent radii such that the OPC areas do not to face each other.

Each of the information storage layers further includes a defectmanagement area (DMA) and a data area in which user data is recorded.

FIG. 3A illustrates a dual-layered information storage medium whichincludes first and second information storage layers L0 and L1. Thefirst information storage layer L0 includes a first OPC area 20_L0, afirst DMA 23_L0, and a first data area 35_L0, and the second informationstorage layer L1 includes a second OPC area 20_L1, a second DMA 23_L1,and a second data area 35_L1.

The first and second OPC areas 20_L0 and 20_L1 are located withindifferent radiuses of the information storage medium. First buffer areas19_L0 and 21_L0 are disposed in front of and behind the first OPC area20_L0, respectively. Second buffer areas 19_L1 and 21_L1 are disposed infront of and behind the second OPC area 20_L1, respectively.

Preferably, but not always required, the first and second buffer areas19_L0, 21_L0, 19_L1, and 21_L1 have lengths sufficient to cover atolerance necessary for manufacturing an information storage medium. Thetolerance is obtained in consideration of at least one of three factors:an error in the determination of the start position of each area; thesize of a beam for recording and reproduction; and eccentricity. Theerror in the determination of the start position of each area isgenerated during mastering of the information storage medium and has asize of about 100 μm. In an information storage medium having no bufferareas between areas, when data is recorded on or reproduced from atrack, an adjacent track is affected by a beam spot because the radiusof the beam spot is typically greater than a track pitch. Thus, a bufferarea is placed between areas. The size of the buffer area may bedetermined in consideration of the size of a recording and reproducingbeam so as to prevent an influence of the recording and reproducingbeam.

If the information storage medium used is manufactured with an error,the first and second buffer areas 19_L0, 21_L0, 19_L1, and 21_L1 preventthe first and second OPC areas 20_L0 and 20_L1 from affecting otherareas.

The first and second OPC areas 20_L0 and 20_L1 are disposed withindifferent radii so that the first and second OPC areas 20_LO and 20_L1do not to face each other. In other words, the first OPC area 20_L0faces a reserved area 30_L1, and the second OPC area 20_L1 faces areserved area 30_L0.

The first and second OPC areas 20_L0 and 20_L1 are manufactured to bespaced apart from each other by a distance corresponding to no less thanan allowable eccentricity amount in the radial direction of theinformation storage medium. In other words, a difference betweenlocations of the first and second OPC areas 20_L0 and 20_L1 in theradial direction is no less than the allowable eccentricity amount. Thedifference between the locations of the first and second OPC areas 20_L0and 20_L1 denotes a distance between a rear end of the first OPC area20_L0 and a front end of the second OPC area 20_L1.

Referring to FIG. 3A, the first and second buffer areas 19_L1 and 21_L0preferably are separated by a distance corresponding to no less than anallowable eccentricity amount.

The dual-layered information storage medium of FIG. 3A further includesat least one pair of a pair of buffer areas 31_L0 and 31_L1 and a pairof buffer areas 32_L0 and 32_L1 and reserved areas 30_L0 and 30_L1. Thereserved areas 30_L0 and 30_L1 may not be included. The buffer areas aredisposed between the reserved area 30_L0 (or 30_L1) and the OPC area20_L0 (or 20_L1) and between the DAM 23_L0 (or 23_L1) and the data area35_L0 (or 35_L1).

In the dual-layered information storage medium of FIG. 3A, buffers aredisposed on both sides of each of the first and second OPC areas 20_L0and 20_L1 of the corresponding first and second information storagelayers L0 and L1. Preferably, this principle is equally applied to asingle-layered information storage medium of FIG. 3B.

Referring to FIG. 3B, the single-layered information storage mediumincludes an OPC area 20 and buffer areas 19 and 21 disposed on bothsides of the OPC area 20. The single-layered information storage mediumfurther includes a reserved area 30, a DMA 23, and a data area 35. Asillustrated in FIG. 3B, a buffer area 31 is interposed between thereserved area 30 and the DMA 23, and a buffer area 32 is interposedbetween the DMA 23 and the data area 35.

To prevent an influence of eccentricity upon the information storagemedium shown in FIG. 3A, each of the first and second buffer areas19_L0, 21_L0, 19_L1, and 21_L1 has a size corresponding to the allowableeccentricity amount. Accordingly, even when the first and secondinformation storage layers L0 and L1 are made eccentric by the maximumamount in the range of the allowable eccentricity amount, the OPC areas20_L0 and 20_L1 of the first and second information storage layers,respectively, are arranged such that the OPC areas 20_L0 and 20_L1 donot face each other.

In an information storage medium with a 120 mm diameter, the allowableeccentricity amount is in the range of about 70-80 μm. In an informationstorage medium with a 60 mm diameter, the allowable eccentricity amountis in the range of about 20-30 μm. The allowable eccentricity amountvaries depending on the size of an information storage medium. Hence,the first and second buffer areas 19_L0, 21_L0, 19_L1, and 21_L1 havesizes in the range of 5 to 100 μm so as to cover the allowableeccentricity amounts of all possible kinds of information storage media.

FIGS. 4A and 4B illustrate the first and second information storagelayers L0 and L1, which are made eccentric by the maximum amount withinthe range of the allowable eccentricity amount. FIG. 4A illustrates thefirst and second information storage layers L0 and L1 made eccentrictoward the inner and outer boundaries, respectively, of the informationstorage medium of FIG. 3A. FIG. 4B illustrates the first and secondinformation storage layers L0 and L1 made eccentric toward the outer andinner boundaries, respectively, of the information storage medium ofFIG. 3A.

Referring to FIG. 4A, when the information storage medium of FIG. 3A isin a maximal eccentric state, the first OPC area 20_L0 faces the bufferarea 31_L1 (see circle A) or the reserved area 30_L1 instead of thesecond OPC area 20_L1. Similarly, the second OPC area 20_L1 faces thebuffer area 31_L0 (see circle B) or the reserved area 30_L0 instead ofthe first OPC area 20_L0.

Referring to FIG. 4B, when the information storage medium of FIG. 3A isin a maximal eccentric state, the first OPC area 20_L0 faces the bufferarea 19_L1 (see circle A′), and the second OPC area 20_L1 faces thebuffer area 21_L0 (see circle B′).

As described above, even when the information storage medium of FIG. 3Ais in a maximal eccentric state, the first and second OPC areas 20_L0and 20_L1 do not face each other and accordingly do not affect eachother during a test for optimal power control. Of course, when theinformation storage medium as shown in FIG. 3A is not made eccentric,the first and second OPC areas 20_L0 and 20_L1 do not affect each otherbecause they are originally disposed not to face each other.

The above-described layout of the dual-layered information storagemedium of FIG. 3A can be equally applied to an information storagemedium having more than two information storage layers. In other words,in an information storage medium having at least four informationstorage layers, odd-numbered information storage layers each have thelayout of the first information storage layer L0 of FIG. 3A, andeven-numbered information storage layers each have the layout of thesecond information storage layer L1 of FIG. 3A.

FIG. 5A illustrates a four-layered information storage medium havingfirst, second, third, and fourth information storage layers L0, L1, L2,and L3, respectively. The first, second, third, and fourth informationstorage layers L0, L1, L2, and L3 include OPC areas 20_L0, 20_L1, 20_L2,and 20_L3, respectively, DMAs 23_L0, 23_L1, 23_L2, and 23_L3,respectively, areas 35_L0, 35_L1, 35_L2, and 35_L3, respectively.

If an information storage medium has a plurality of information storagelayers, it has an odd-numbered information storage layer(s) and aneven-numbered information storage layer(s). OPC areas 20_L1 and 20_L3included in the odd-numbered information storage layer are referred toas first OPC areas, and OPC areas 20_L0 and 20_L2 included in theeven-numbered information storage layer are referred to as second OPCareas. The first and second OPC areas in the odd-numbered andeven-numbered information storage layers, respectively, are disposedwithin different radiuses of the information storage medium. A pair ofbuffer areas 19_L0 and 21_L0, a pair of buffer areas 19_L1 and 21_L1, apair of buffer areas 19_L2 and 21_L2, and a pair of buffer areas 19_L3and 21_L3 for preventing an influence of the OPC due to eccentricity aredisposed on both sides of each of the OPC areas 20_L0, 20_L1, 20_L2, and20_L3, respectively.

Reserved areas 30_L0, 30_L1, 30_L2, and 30_L3 are further included, andbuffer areas 31_L0, 31_L1, 31_L2, and 31_L3 may be further disposedadjacent to the reserved areas 30_L0, 30_L1, 30_L2, and 30_L3.

FIG. 5B illustrates an eccentric state of the four-layered informationstorage medium of FIG. 5A. Even when an information storage mediumhaving at least three information storage layers is made eccentric, OPCareas in adjacent information storage layers do not face each other asillustrated in circles E and F of FIG. 5B. Hence, an influence of theOPC executed in an OPC area upon another OPC area can be prevented.

Referring to FIG. 6A, a variation of the dual-layered informationstorage medium of FIG. 3A includes at least one information storagelayer which includes an OPC area for obtaining optimal power, a DMA, anda data area in which user data is recorded. A buffer area is disposedadjacent to the OPC area toward an inner or outer boundary of theinformation storage medium.

The dual-layered information storage medium of FIG. 6A includes firstand second information storage layers L0 and L1. The first and secondOPC areas 20_L0 and 20_L1 of the first and second information storagelayers L0 and L1 are disposed within different radiuses of theinformation storage medium such that the first and second OPC areas20_L0 and 20_L1 do not to face each other. The first and second OPCareas 20_L0 and 20_L1 are disposed to be spaced apart from each other inthe radial direction of the information storage medium by a distancecorresponding to at least a maximum eccentricity amount.

The first buffer area 21_L0 is disposed on a side of the first OPC area20_L0 that faces the outer boundary of the information storage medium,and the second buffer area 19 _L1 is disposed on a side of the secondOPC area 20_L1 that faces the inner boundary of the information storagemedium. When the information storage medium has no eccentricity, thefirst and second buffer areas 21_L0 and 19 _L1 face each other. Thefirst and second buffer areas 21_L0 and 19 _L1 have a lengthcorresponding to at least the maximum eccentricity amount. The reservedareas 30_L0 and 30_L1 are disposed adjacent to the first and secondbuffer areas 21_L0 and 19 _L1.

In the information storage medium of FIG. 6A, no buffer areas areincluded between the DMA 23_L0 and the data area 35_L0 and between theDMA 23_L1 and the data area 35_L1. Thus, the information storage mediumof FIG. 6A provides more area for storing user data than the informationstorage medium of FIG. 3A.

FIGS. 6B and 6C illustrate different maximum eccentric states of thedual-layered information storage medium of FIG. 6A. When the first andsecond information storage layers L0 and L1 are made eccentric towardthe inner and outer boundaries, respectively, of the information storagemedium of FIG. 6A as shown in FIG. 6B, the second OPC area 20_L1 facesthe DMA 23_L0 in the first information storage layer L0.

When the first and second information storage layers L0 and L1 are madeeccentric toward the outer and inner boundaries, respectively, of theinformation storage medium of FIG. 6A as shown in FIG. 6C, the first OPCarea 20_L0 faces the buffer area 19 _L1 of the second informationstorage layer L1, and the second OPC area 20_L1 faces the buffer area21_L0 in the first information storage layer L0. In other words, in thiscase, the first and second OPC areas 20_L0 and 20_L1 never face eachother even when the information storage medium of FIG. 6A is madeeccentric. Thus, the first and second OPC areas 20_L0 and 20_L1 do notaffect each other. Also, a recording capacity of the information storagemedium of FIG. 6A can be increased by reducing the buffer area as muchas possible.

FIG. 7A illustrates another embodiment of the dual-layered informationstorage medium of FIG. 3A. Referring to FIG. 7A, the first and secondinformation storage layers L0 and L1 include first and second OPC areas40_L0 and 40_L1, respectively, DMAs 42_L0 and 42_L1, respectively, anddata areas 44_L0 and 44_L1, respectively. A buffer area 39_L0 and afirst reserved area 41_L0 are disposed at both sides of the first OPCarea 40_L0, and a buffer area 41_L1 and a second reserved area 39_L1 aredisposed at both sides of the second OPC area 40_L1. The informationstorage medium of FIG. 7A is the same as that of FIG. 3A in that thefirst and second OPC areas 40_L0 and 40_L1 are disposed within differentradiuses. In contrast with FIG. 3A, the first and second reserved areas41_L0 and 39_L1 of FIG. 7A have different sizes than the reserved areas30_L and 30_L1 of FIG. 3A. In FIG. 3A, the buffer area 21_L0, thereserved area 30_L0, and the buffer area 31_L0 are sequentially disposedon a side of the first OPC area 20_L0 that faces the outer boundary.Similarly, in FIG. 7A, the first reserved area 41_L0, which has a lengthcorresponding to the reserved area 30_L0 and the buffer areas 21_L0 and31_L0, is disposed on a side of the first OPC area 40_L0 that faces theouter boundary.

Also, in FIG. 3A, the buffer area 31_L1, the reserved area 30_L1, andthe buffer area 21_L1 are sequentially disposed on a side of the secondOPC area 20_L1 that faces the inner boundary. Similarly, in FIG. 7A, thesecond reserved area 39_L1, which has a length corresponding to thereserved area 30_L1 and the buffer areas 21_L1 and 31_L, is disposed ona side of the second OPC area 40_L1 that faces the inner boundary.

As described above, the information storage media according to thevarious embodiments are manufactured so that OPC areas in adjacentinformation storage layers are located within different radiuses andthat each of the OPC areas face a reserved area or a buffer area,thereby preventing a recording property from being degraded due to OPC.Preferably, the reserved area or the buffer area that faces each of theOPC areas is longer than each of the OPC areas.

FIG. 7B illustrates another embodiment of the single-layered informationstorage medium of FIG. 3B. To have a consistency with the dual-layeredinformation storage medium of FIG. 7A, the single-layered informationstorage medium of FIG. 7B includes an OPC area 40, a buffer area 39disposed at one side of the OPC area 40, and a reserved area 41 disposedat the other side of the OPC area 40. A DMA 42, a buffer area 43, and adata area 44 are disposed adjacent to the reserved area 41. In thisembodiment, the reserved area 41 is larger than the buffer area 39.

FIG. 8 illustrates a layout of a data area of a dual-layered informationstorage medium according to another embodiment of the present invention.The dual-layered information storage medium of FIG. 8 includes first andsecond information storage layers L0 and L1. A second OPC area 47_L1 forcontrolling optimal recording power is included in the secondinformation storage layer L1, and a first reproduction-only area 50_L0for storing reproduction-only data is disposed at a location of thefirst information storage layer L0 that faces the second OPC area 47_L1.The first reproduction-only area 50_L0 is larger than the second OPCarea 47_L1. Examples of the reproduction-only data include adisc-related information and disk control data.

The first information storage layer L0 further includes a firstprotection area 51_L0 and a first OPC area 47_L0, between buffer areas45_L0 and 48_L0. The second information storage layer L1 furtherincludes buffer areas 45_L1 and 48_L1, a second protection area 51_L1,and a second reproduction-only area 50_L1. The buffer areas 45_L1 and48_L1 are disposed at both sides of the second OPC area 47_L1.

The first and second protection areas 51_L0 and 51_L1 are used to obtainthe time during which a disk drive accesses each area of a disk. Inother words, a protection area is allocated to transit an area toanother area in the radial direction of a disk.

Each of the first and second buffer areas 45_L0, 45_L, 48_L0, and 48_L1has a length sufficient to cover a tolerance necessary for manufacturingan information storage medium. The tolerance is obtained inconsideration of at least one of three factors: an error in thedetermination of the start position of each area; the size of a beam forrecording and reproduction; and eccentricity. The error in thedetermination of the start position of each area is generated duringmastering and has a size of about 100 μm. In an information storagemedium having no buffer areas between areas, when data is recorded on orreproduced from a track, an adjacent track is affected by a beam spotbecause the radius of the beam spot is typically greater than a trackpitch. Thus, a buffer area is placed between areas in embodiments of thepresent invention. The size of the buffer area may be determined inconsideration of the size of a recording and reproducing beam so as toprevent an influence of the recording and reproducing beam.

To prevent an influence of the OPC from an adjacent information storagelayer, the first OPC area 47_L0 in the first information storage layerL0 is located to face the second reproduction-only area 50_L1, and thesecond OPC area 47_L1 in the second information storage layer L1 islocated to face the first reproduction-only area 50_L0.

Disk-related information and disk control data, which are examples ofreproduction-only data, may be recorded many times in the first andsecond reproduction-only areas 50_L0 and 50_L1 in order to increase thereliability of information. In this case, to face an area correspondingto at least one pair of disk-related information and disk control data,each of the buffer areas 45_L0 and 45_L1 is longer than a pair ofdisk-related information and disk control data for one recording.

Because the recording of a reproduction-only area is rarely affected bythe OPC process, the area is located directly over or below an OPC areain the information storage medium of FIG. 8. Thus, while thereproduction-only area is used to prevent an influence of OPC in an OPCarea upon another OPC area, the reproduction only area is also used as adata area. Also, because the first and second OPC areas 47_L0 and 47_L1as arranged never face each other even when eccentricity occurs in theinformation storage medium of FIG. 8, performing an OPC process in anOPC area does not affect another OPC area which is on a different layer.

FIG. 9 illustrates a variation of the dual-layered information storagemedium of FIG. 8 in the dual-layered information storage medium of FIG.9, a first information storage layer L0 includes the firstreproduction-only area 50_L0 of FIG. 8, in which disk-relatedinformation for reproduction-only and disk control data forreproduction-only are recorded, and a first protection area 51_L0. Asecond information storage layer L1 includes an OPC area 47_L1 thatfaces the first reproduction-only area 50_L0. First and second bufferarea 45_L1 and 49_L1 are disposed at both sides of the OPC area 47_L1.The information storage medium of FIG. 9 is different from that of FIG.8 in that the second buffer area 49_L1 is sized to approximate the sizeof the second buffer 48_L1 of FIG. 8 and the second protection area51_L1 of FIG. 8. As described above, the buffer area may have varioussizes depending on its purpose, use, or the like.

Even if the information storage media of FIGS. 8 and 9 are madeeccentric, or an error is generated in a location of each of theinformation storage media of FIGS. 8 and 9 where each area starts, theOPC area 47_L1 always faces the first reproduction-only area 50_L0.Hence, the reproduction-only area 50_L0 prevents the OPC in an OPC areaof a layer from affecting an area of an adjacent layer and is used as adata area.

FIG. 10 is a block diagram of a recording and/or reproducing apparatusin which the information storage media of FIGS. 3-9 are implemented.Referring to FIG. 10, the recording and/or reproducing apparatusincludes a writer/reader unit 100 and a controller 120. Thereader/writer unit 100 reads from and writes to the information storagemedium 130 according to commands from the controller 120.

FIG. 11 is a more detailed block diagram of the recording and/orreproducing apparatus of FIG. 10. Referring to FIG. 11, the informationstorage medium 130 is loaded in the reader/writer unit 100. Thereader/writer unit 100 includes an optical pickup 110 which reads fromand writes to the information storage medium 130. The recording and/orreproducing apparatus further includes a PC I/F 121, a DSP 122, an RFAMP 123, a servo 124, and a system controller 125, all of whichconstitute the controller 120.

Upon a recording operation being initiated, the PC I/F 121 receives arecording command together with data to be recorded, from a host (notshown). The system controller 125 performs the initialization necessaryfor recording, such as determining an OPC. More specifically, the systemcontroller 125 reads out information necessary for initialization, suchas, disk-related information stored in a lead-in area of an informationstorage medium 130, and prepares for recording based on the read-outinformation. The DSP 122 performs ECC encoding on the to-be-recordeddata received from the PC I/F 121 by adding data such as parity to thereceived data, and then modulates the ECC-encoded data in a specifiedmanner. The RF AMP 123 converts the data received from the DSP 122 intoan RF signal. The pickup 110 records the RF signal received from the RFAMP 123 to the information storage medium 130. The servo 124 receives acommand necessary for servo control from the system controller 125 andservo-controls the pickup 110. If the information storage medium 130stores no reproducing speed information, the system controller 125commands the pickup 110 to write the reproducing speed information to aspecified area of the information storage medium 130 when recordingstarts, while recording is being executed, or after recording has beencompleted.

Upon a reproduction operation being initiated, the PC I/F 121 receives areproduction command from the host (not shown). The system controller125 performs the initialization necessary for reproduction. When theinitialization is completed, the system controller 125 reads outreproducing speed information recorded on the information storage medium130 and performs reproduction at a reproducing speed corresponding tothe read-out reproducing speed information. The pickup 110 projects alaser beam onto the information storage medium 130, receives a laserbeam reflected by the information storage medium 130, and outputs anoptical signal. The RF AMP 123 converts the optical signal received fromthe pickup 110 into an RF signal, supplies modulated data obtained fromthe RF signal to the DSP 122, and supplies a servo control signalobtained from the RF signal to the servo 124. The DSP 122 demodulatesthe modulated data and outputs data obtained through ECC errorcorrection. The servo 124 receives the servo control signal from the RFAMP 123 and a command necessary for servo control from the systemcontroller 125 and servo-controls the pickup 110. The PC I/F 121 sendsdata received from the DSP 122 to the host (not shown).

A method of recording data to an information storage medium havingmultiple layers according to an embodiment of the present inventioncomprising recording data in the optimal power control area andobtaining an optical recording condition. The optimal power controlareas are disposed in adjacent ones of the information storage layerswithin different radiuses of the information storage medium such thatinterference among the optimal power control areas is prevented.

As described above, even when an information storage medium according tothe present invention is made eccentric or has a manufacturing error, arecording property of the information storage medium is prevented frombeing degraded due to an influence of an OPC area in an informationstorage layer upon an OPC area in an adjacent information storage layer.

Although a few embodiments of the present invention have been shown anddescribed, it would be appreciated by those skilled in the art thatchanges may be made in these embodiments without departing from theprinciples and spirit of the invention, the scope of which is defined inthe claims and their equivalents.

1. A reproducing apparatus, comprising: an optical pickup which readsdata from storage layers of a storage medium; and a controller whichcontrols the optical pickup to read reproducing and/or recording speedinformation on the storage medium and to reproduce and/or record thedata from the storage layers of the storage medium at a reproducingand/or recording speed, wherein each of the storage layers includes anoptimal power control area for use in obtaining an optical recordingcondition, and one of a buffer area and a reserved area disposed at oneside of the optimal power control area, and wherein the optimal powercontrol areas in adjacent ones of the storage layers are disposed withindifferent radii of the storage medium such that one of the buffer areaand the reserved area disposed in one of the storage layers faces theoptimal power control area disposed in an adjacent one of the storagelayers.
 2. The apparatus of claim 1, wherein each of the storage layersfurther comprises another buffer disposed on an opposite side of each ofthe optimal power control areas.
 3. The apparatus of claim 2, whereinthe reserved area is disposed adjacent to one of the buffer areasdisposed at one side of the optimal power control area in one of thestorage layers such as to face the optimal power control area in anadjacent one of the storage layers.
 4. The apparatus of claim 1, whereineach of the storage layers further comprises a plurality of datarecording areas and another buffer area interposed between adjacentdata-recording areas.
 5. The apparatus of claim 1, wherein each of thestorage layers further comprises a defect management area, a user dataarea, and another buffer area disposed between the defect managementarea and the user data area.
 6. The apparatus of claim 2, wherein alength of each of the buffer areas in the radial direction of thestorage medium is in the range of 5 to 100 μm.
 7. The apparatus of claim1, wherein a reproduction-only area storing reproduction-only data isdisposed in one of the storage layers such that the reproduction-onlyarea faces the optimal power control area of the adjacent one of thestorage layers.
 8. The apparatus of claim 7, wherein disk-relatedinformation and disk control data are recorded in the reproduction-onlyarea for storing the reproduction-only data.
 9. A storage mediumcomprising: a plurality of storage layers, each including an optimalpower control area used for obtaining an optimum recording condition,buffer areas and a reproduction-only area storing reproduction-onlydata, and wherein the reproduction-only area of one of the storagelayers is arranged to face the optical power control area and the bufferareas of an adjacent one of the storage layers.
 10. The storage mediumof claim 9, wherein the reproduction-only area of the one of the storagelayers is larger than the optimal power control area of the adjacent oneof the storage layers.
 11. The storage medium of claim 9, wherein thebuffer areas are disposed at both sides of each of the optimal powercontrol areas.